Geneticists reconstruct the genome of the deadly Black Death plague

The Black Death, the devastating bubonic epidemic that killed
off 50 million Europeans in the 14th century, has had its
700-year-old genome reconstructed
by an international team of geneticists.

The researchers dug up Black Death victims who were buried in
the East Smithfield "plague pits" in London, deep beneath what is
now the Royal Mint. The team extracted tiny scraps of the guilty
pathogen Yersinia
pestis' DNA from the specimen's dental pulp, while leaving
behind other contaminating genetic code.

From these DNA fragments, the researchers were able to piece
together the plague pathogen's genetic blueprints, allowing them to
reconstruct almost all of the Black Death genome. This marks the
first time that scientists have been able to draft a reconstructed
genome of any ancient pathogen.

The ambitious task has serious consequences for humans battling
disease, today. "The genomic data show that this bacterial strain,
or variant, is the ancestor of all modern plagues we have today
worldwide," said director Michael DeGroote of the McMaster Ancient
DNA Centre. "Every outbreak across the globe today stems from a
descendant of the medieval plague."

The direct descendants of the same bubonic plague continue to
exist and terrorise today, killing about
2,000 people each year.

"The next step is to determine why this was so deadly," said
geneticist Hendrik Poinar of McMaster University. "We found that in
660 years of evolution as a human pathogen, there have been relatively few
changes in the genome of the ancient organism, but those changes,
however small, may or may not account for the noted increased
virulence of the bug that ravaged Europe."